A junction box is used to concentrate electric circuit components such as a fuse, a relay or the like in a motor vehicle. The junction box includes a plurality of electric circuits connected to respective electric devices of a motor vehicle.
As illustrated in FIGS. 1 to 3, the junction box includes a main body 10 to which a plurality of circuit components E are mounted, an upper cover 20 which covers the upper portion of the main body 10, a lower cover 30 which covers the lower portion of the main body 10, a plurality of sockets 12 which are installed on the lower surface of the main body 10 so as to be connected to the circuit components E, and a plurality of connectors 32 which are installed in the lower cover 30 so as to be coupled to the sockets 12.
The junction box further includes a plurality of coupling bolts 40 installed in the main body 10 and a plurality of coupling nuts 42 installed in the respective connectors 32 so as to be threadedly coupled to the coupling bolts 40.
The coupling bolts 40 are installed in the main body 10 so as to protrude toward the respective connectors 32 of the lower cover 30. The coupling bolts 40 thus installed are threadedly coupled to the coupling nuts 42 of the connectors 32.
If the coupling bolts 40 threadedly coupled to the coupling nuts 42 are rotated in a forward direction by a worker, the coupling nuts 42 are moved upward along the coupling bolts 40 while making screw motion. The coupling nuts 42 cause the connectors 32 to move upward. This enables the respective connectors 32 of the lower cover 30 to be coupled to the corresponding sockets 12 existing above the connectors 32.
On the other hand, if the coupling bolts 40 are rotated in a reverse direction, the coupling nuts 42 are moved downward along the coupling bolts 40 while making screw motion. The coupling nuts 42 cause the connectors 32 to move downward. This enables the respective connectors 32 to be decoupled from the corresponding sockets 12 existing above the connectors 32.
Consequently, the coupling bolts 40 and the coupling nuts 42 cause the connectors 32 of the lower cover 30 to move upward or downward in response to the worker's operation, thereby coupling or decoupling the connectors 32 and the sockets 12.
However, in the conventional junction box described above, the bolting units of the coupling bolts 40 and the coupling nuts 42 for coupling and decoupling the connectors 32 and the sockets 12 are installed in each and every connector 32. Thus, the junction box becomes structurally complicated and requires a large number of components. This leads to an increase in the manufacturing cost.
Since the bolting units of the coupling bolts 40 and the coupling nuts 42 are installed in each and every connector 32, the respective coupling bolts 40 should be individually operated one by one in order to couple and decouple the respective connectors 32 and the respective sockets 12. Thus, the coupling and decoupling works of the connectors 32 and the sockets 12 is very onerous and time-consuming.
Furthermore, since the bolting units of the coupling bolts 40 and the coupling nuts 42 are installed in each and every connector 32, different installation spaces for accommodating the bolting units of the coupling bolts 40 and the coupling nuts 42 need to be provided in the connectors 32 and the main body 10. This leads to a loss of spaces.
Particularly, in the case of the main body 10 and the connectors 32, the spaces for installation of electric circuits become narrow due to the existence of the bolting units of the coupling bolts 40 and the coupling nuts 42. This may impose many restrictions on the configuration of electric circuits.
Moreover, in the conventional junction box, when moving the connectors 32 upward and downward by the bolting units, variations occur in the upward/downward movement amounts of the respective connectors 32.
Particularly, the portions of the connectors 32 existing far away from the bolting units is smaller in the upward/downward movement amounts than the portion of the connectors 32 existing close to the bolting units. Due to these variations in the upward/downward movement amounts, the coupling accuracy of the connectors 32 to the sockets 12 is sharply reduced. For that reason, the connectors 32 may not be coupled to the sockets 12 or may be inaccurately coupled to the sockets 12.
In addition, the conventional structure has a structure in which the connectors 32 are coupled to and decoupled from the sockets 12 while making up/down movement. Therefore, the length of wire harnesses 32a connected to the connectors 32 needs to be designed and set in view of the up/down movement stroke of the connectors 32.
Since the length of wire harnesses 32a is designed and set in view of the up/down movement stroke of the connectors 32, the manufacturing cost increased.
In view of the foregoing, there have been developed many different techniques capable of making it easy to couple and decouple the connectors 32 and the sockets 12, reducing the loss of spaces, and increasing the installations spaces for terminals and circuit components.
Examples of these techniques include a junction box disclosed in Korean Patent Application No. 2006-112772. In this junction box, as illustrated in FIG. 4, connectors 32 and sockets 12 are coupled and decoupled using a lever 50. The junction box includes a lever 50 installed in an upper cover 20 in a foldable manner, a pair of sliders 52 installed in a main body 10 so as to horizontally move in conjunction with the unfolding operation of the lever 50, and a combination of guide slots 54 of the sliders 52 and guide projections 56 of a lower cover 30 configured to convert the horizontal movement of the sliders 52 to the up/down movement thereof.
The guide slots 54 and the guide projections 56 are combined so as to make frictional contact with each other. The guide slots 54 and the guide projections 56 are configured to convert the horizontal movement of the sliders 52 to the up/down movement thereof.
Accordingly, when folding and unfolding the lever 50, the main body 10 provided with the sliders 52 are moved up and down. Thus, the sockets 12 of the main body 10 are moved up and down and are coupled to and decoupled from the connectors 32 existing below the sockets 12.
The conventional junction box having the aforementioned configuration is easy to use, because the sockets 12 of the main body 10 and the connectors 32 of the lower cover 30 can be automatically coupled and decoupled by merely folding and unfolding the lever 50.
While the conventional junction box has a merit in that it is easy to couple and decouple the sockets 12 and connectors 32 and it is advantageous to form electric circuits, the structures of the lever 50 and the sliders 52 for moving the main body 10 up and down are very complex. This leads to an increase in the manufacturing cost.
Furthermore, there is a need to additionally provide installation spaces for the installation of the lever 50 and the sliders 52. Thus, the overall size of the junction box is necessarily increased.
For that reason, the junction box occupies a large space when installing the junction box in a motor vehicle. As a result, it is not possible to cope with the trend of size reduction and slimming of the junction box required for the reduction of an internal space of a motor vehicle.
Furthermore, the conventional junction box has a structure in which the sockets 12 and the connectors 32 are coupled and decoupled by folding and unfolding the lever 50. Thus, it is necessary to secure a space for folding and unfolding the lever 50. For that reason, the junction box cannot be installed in a motor vehicle having a narrow installation space.
Moreover, during the course of folding and unfolding the lever 50, a heavy load is applied to between the lever 50 and the sliders 52 and between the sockets 12 and the connectors 32. Thus, it is highly likely that the lever 50, the sliders 52, the sockets 12 and the connectors 32 are damaged or broken.
In view of this, the frictional contact portions between the lever 50 and the sliders 52 and the frictional contact portions between the sockets 12 and the connectors 32 may be made of a high-strength material such as, for example, steel or a composite material. In this case, however, there is a possibility that a short circuit is generated and a cost is increased.
In addition, the conventional junction box has a structure in which the sockets 12 and the connectors 32 are coupled and decoupled through the rotation of the lever 50, the horizontal movement of the sliders 52 and the frictional contact of the guide slots 54 and the guide projections 56. Thus, the frictional contact portions between the lever 50 and the sliders 52 and the frictional contact portions between the sockets 12 and the connectors 32 are worn.
As a result, the assembly accuracy of components is reduced and the dimensional error is generated. For that reason, the main body 10 is not smoothly moved up and down and the coupling accuracy of the connectors 32 and the sockets 12 is reduced. Thus, the connectors 32 may not be coupled to the sockets 12 or may be inaccurately coupled to the sockets 12.